Abstract

A new method for real-time edge enhancement and image equalization using photochromic filters is presented. The reversible self-adaptive capacity of photochromic materials is used for creating an unsharp mask of the original image. This unsharp mask produces a kind of self filtering of the original image. Unlike the usual Fourier (coherent) image processing, the technique we propose can also be used with incoherent illumination. Validation experiments with Bacteriorhodopsin and photochromic glass are presented.

Figures (12)

Setup for unsharp masking using a photochromic filter. M is the photochromic filter (mask) placed at the defocused plane ∑, L is an imaging lens, I0 is the image to be processed, and Iout is the processed image.

Steady-state transmittance of BR for light of wavelength λV=405nm, when light of wavelength λG=532nm is incident. Ith is a threshold intensity and Ts a saturation transmittance. The circles are the experimental data, and the continuous curve is the fitting using Eq. (5).

Steady-state transmittance of a photochromic glass slab for light of wavelength 405nm, when light of wavelength ∼388nm is incident. Ith is a threshold intensity and a saturation transmittance. The circles are the experimental data, and the continuous curve is the fitting using Eq. (5).

(a) Output intensity distribution Iout obtained experimentally using photochromic glass filter; (b) the continuous curve shows a one-dimensional intensity cut parallel to one of the square sides of the output image shown in (a). The dotted curve is a numerical simulation using Eq. (6), for which the original pattern shown in 8b was considered as input.